Milk, which is nutritious, is a universal food. However, a large number of people have difficulty in digesting lactose, a major nutrient of milk, owing to lack of lactase, β-galatosidase. To solve this problem, lactase is added to milk during milk processing.
In spite of such an effort, most consumers do not prefer milk containing lactase because hydrolysis of lactose mediated by lactase increases the sweetness of milk to several times higher than normal milk.
In order to solve this problem, there was employed a microencapsultion method by which enzymes are microencapsulated, but uncapsulated enzymes remains in dispersion fluid to hydrolyze lactose, thus they increase sweetness of milk. For this reason, residual enzymes should be eliminated.
It was reported that the residual enzymes can be removed by centrifugation (H. S., Kwak, M. R. Ihm, and J. Ahn., 2001. Microcapsulation of β-galactosidase with fatty acid esters. J. Dairy Sci. 84:1576–1582). However, the centrifugation method has conspicuous disadvantages of being non-economical industrially owing to high cost large-scale centrifuges, and high production cost resulting from requirement of two or three centrifugation steps.